Roof bit coupling

Abstract

A quick release, high torque coupling for interconnecting the bit and drive member in a mine roof drill has axial-locking and torque-transmitting structure integral with the drill members. A plug on the drive member is adapted to be releasably received within a mating socket in the bit and has an axial-locking segment on its outermost end complementally configured with respect to an acircular constriction in the socket to permit insertion of the axial-locking segment into the socket beyond the constriction. A torque transmitting segment on the plug cooperates with the constriction to limit relative rotation of the bit and drive member between oppositely directed torque-transmitting positions. In one of the torque-transmitting positions, the constriction and axial-locking segment are misaligned such that the plug is restrained against axial retraction from the socket.

What I claim is: 
     
       1. In a mine roof drilling system of the type having a drive member and a bit member, a high torque coupling for releasably interconnecting said members for rotation about a common axis, said coupling including: a plug on one of said members projecting axially from an end thereof and having an outermost axial-locking segment and a discrete torque-transmitting segment;   a socket in one end of the other said members adapted to releasably receive said plug with said members axially aligned; and   a radial constriction in said socket, said constriction having an acircular transverse cross-section;   said axial-locking segment having a transverse cross-section complemental to said acircular cross-section of the constriction to permit the axial-locking segment to pass through the restriction when the cross-sections are aligned for insertion or withdrawal of the plug from the socket;   said torque-transmitting segment having an acircular transverse cross-section dissimilar to the cross-section of said restriction and cooperable therewith to permit limit relative rotation of said members with respect to one another between right- and left-hand torque-transmitting positions when the plug is received within the socket;   said axial-locking segment being angularly positioned about the axis of said one member relative to said torque-transmitting member such that the locking-segment is angularly misaligned with said restriction when the members are in one of said torque-transmitting positions whereby to preclude withdrawal of the plug from the socket by solely axial movement.   
     
     
       2. The invention of claim 1, and stop means for precluding insertion of the torque-transmitting segment of the plug beyond the restriction in the socket. 
     
     
       3. The invention of claim 1, wherein said axial-locking segment is angularly aligned with said restriction when said members are in the other of said torque-transmitting positions. 
     
     
       4. The invention of claim 1, wherein a single reference regular polygon defines a part of each of said acircular transverse cross-sections. 
     
     
       5. The invention of claim 4, the transverse cross-section of said torque-transmitting segment being formed by removing the area of said reference polygon between its inscribed circle and the periphery of the polygon at selected corners such that there remains only non-adjacent corners of the original polygon. 
     
     
       6. The invention of claim 5, the transverse cross-section of said axial-locking segment being formed by adding to the reference polygon the area between the circumscribed circle of the polygon and its periphery at selected sides of the reference polygon such that there remains only non-adjacent sides of the original polygon. 
     
     
       7. The invention of claim 5, wherein said reference polygon is a hexagon.